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Ecolo21 Co., a taxi company in the Kyoto region of Japan started an interesting new service earlier this year, allowing passengers to charge their cell phones using the electricity generated by a wind turbine mounted on a taxi’s roof.
From the Japan for Sustainability web site…
The taxi’s rooftop wind turbine has a built-in generator so that wind energy is converted to electricity. The electricity is stored in the car’s battery and then sent to a cigarette lighter socket. By connecting a charger to the socket, passengers can charge their cell phones. The company installed this system in one of its taxis, and it is planning to install an improved version in its remaining 19 taxis by the autumn of 2005.
The Ecolo21 taxi company prides itself on its “environmentally friendly business practices“. In addition to the roof turbines, they’ve also equipped their fleet of Ecolo-Taxi’s with an idle-stop feature, which temporarily shuts off the engine when it’s idling, and with bike racks to encourage bicycle use.
While I’m happy to see such initiative, I can’t help wondering what kind of drag those roof turbines cause, and whether the increase in fuel use as a result would off-set what’s being saved via cell charging this way. Surely in a place like Japan, a cab company would look to using hybrids, and then you could offer free cell phone charging from power generated off the braking system.
As Jeff at sustainblog pointed in the comments of his post on this, it may be more of a novelty thing.
[via sustainablog]
1399 days ago
A purely cosmetic way of increasing the consumption of fossil fuels!
Simple physics tells us that the generator cannot be 100% effecient therefore more energy must be put into dragging the generator (and its support structure) through the air than it generates.
perpetual motion machines don’t exist!
Stick to a 12V outlet off the cars electical system if you want to offer a value added service without further increasing fuel consumption.
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1781 days ago
[...] [via Unplugged Living] [...]
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1786 days ago
Hey Paul – I figure if this cab company really wanted to be environmentally friendly, one fo the first things they should have done was get rid of the roof racks altogether or at least adopt a design that has some aerodynamics to it.
At the end of the day though, as Jeff pointed out in his orignal post at sustainablog, perhaps it’ll at least provoke some discussion, which could be just as valuable.
Thanks for stopping by, dude!
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1787 days ago
I’m not quite sure about the increased drag thing either. You gotta figure that most cabs already have a large sign on the roof, and in a lot of European and Asian countries that sign is larger than NA because they use them as advertising bilboards.
Adding a small windmill in the center of the sign shouldn’t increase drag too much.
I do fully agree though, that it’s somewhat of a marketing ploy. Why use a wind powered charger when you can just plug into a hotpoint in the car that is constantly charged by the alternator and battery anyway.
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1787 days ago
Hey Tim – I suspect your thoughts make more sense. I can’t see the turbine itself creating much drag, though that roof rack that they’re using isn’t going to help the situation.
Having thought about it, this seems more like a silly marketing ploy than anything of much value. Motor vehicles have such significant kinetic energy, it’d make more sense to tap into that. Besides, how much charge are you going to be able to put into a phone in an average cab ride?
Thanks for offering up your thoughts.
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1788 days ago
I very well might have no idea what I’m talking about, but….. I don’t suspect that there is as much drag as some people might imagine. In aerodynamics this is sometimes called “auto-rotation” and once the turbine starts spinning (overcoming intertia) the blades have momentum. And we know that an object in motion tends to stay in motion unless otherwise disturbed.
There are many other factors at play here too, but something similar is taught to pilots of propeller driven aircraft. In the event of an engine failure you keep the nose of the plane down to maintain enough speed so that the propeller continues to “windmill”. (And for other reasons as well.) If you slow the disabled plane up enough the propeller will stop rotating and drag will significantly increase.
While in this case I think you are correct that the increase in drag might not offset the energy otherwise saved, the increase in drag probably isn’t that much.
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